The ba was a psychic force, one of the five essential parts of the individual person: the ba, the ka, the akh, the name, and the shewet (shadow). The ba is similar in concept to the personality though it is non-physical and also seems to be the divine power. For instance the ram would be the ba of Amun. It could be extended upwards to Wesir (Osiris) being referred to as the ba of Re.

It was necessary for the deceased to rejoin his ka upon death, and since his physical body was now inert it was the job of the ba to make the journey in order for the transformation into the akh. The ba was often portrayed as a human head and arms. This association with the bird led to the belief that migratory birds were the ba flying between the tomb and the netherworld.